Furler foils parted

[D&M]

Hi all
Yesterday when underway, went forward to check on everything. Looked up to see the head sail with a gaping hole near the luff about two feet from the top. From a quick assessment before furling the sail and de-tensioning the headsail it appears as if the top foil has separated from the one beneath it. This looks like it caused enough force on the sail to tear it. Will no more when I get back to the marina in two days. ( Will also post pictures).
From a previous event the lower foil parted and I am aware they are riveted together. My question to everyone is does anyone have details on the exact size needed for the new rivets? I will need to buy some immediately I get to the next marina and want to hit the ground running. Drilling an old one out won’t tell me much. Also are they aluminium or monel.
Any help appreciated.